In order to reduce the manufacturing costs of large scale semiconductor memories, it is desirable to reduce the test time required for testing the memories. Since it is very time consuming to test memories using external circuits only, it has been suggested that internal circuitry be provided on the chip, as part of the memory, for testing memory functionality. Typically, these test circuits operate in a voltage mode, requiring that the analog voltage levels of the memory cell be converted to a CMOS logic level somewhere along the test path. This conversion requires either the use of additional circuits directly connected to the matrix columns or requires that the number of columns tested correspond to the number of sense amplifiers present in the data path. When additional structure is required on the chip, the space available for the matrix of memory cells is decreased. Alternatively, when the number of columns tested is restricted to a few sense amplifiers, a relatively large amount of time is required for testing, because of the limited number of sense amplifiers.
It is therefore desirable to provide a test method which enables the testing of all of the columns of the memory array simultaneously, without the need for adding sense amplifiers.